1. Field of the Invention
The present invention relates to continuous synthetic filaments having a four sided cross-sectional shape containing four continuous voids positioned at distinct locations. The filaments are especially suitable for making carpets which demonstrate improved soiling performance and durability.
2. Description of the Related Art
Those skilled in the art have proposed many different ways to improve the "soiling performance" of continuous synthetic filaments. By the term "soiling performance", it is meant the apparent resistance of a textile material to visible soiling which may be independent of the soiling which actually occurs.
One effort involves producing filaments having continuous voids extending throughout their lengths. As described by Champaneria et al., U.S. Pat. No. 3,745,061, it is known to produce filaments having at least three continuous nonround voids. These voids form about 10% to about 35% of the filament volume and are set against the corners of the filament's cross-sectional contour which is substantially free of re-entrant curves.
W. Lochelfeld et al., German Patent No. DL 90,840/'72 teaches a process for spinning filaments having four hollow spaces. These filaments have high stability due to an approximately circular cross-section. However, the circular cross-section also tends to decrease the bulk of these filaments.
Although such conventional filaments, as described above, have a somewhat effective soiling performance, there is a need for filaments having even greater soiling performance which also demonstrate high bulk and durability. The filaments of the present invention provide an improved combination of soiling performance, bulk, and durability and are especially suitable for carpets receiving a high amount of traffic.